A Review of Technology Readiness Levels for Superconducting Electric Machinery

Round 1

Reviewer 1 Report

This paper describes technologies and TRLs for superconducting electrical machines. In the paper, the technologies are compared very well in terms of materials and in terms of the design of electrical machines. Especially the pros and cons are very well described In the introduction, the fields of application of superconducting electrical machines are very well motivated and the authors refer to applications in aviation, mobility and the military sector. In chapter two, superconductivity in general and the relationship of superconductivity to electrical machines are described. This procedure is summarised very well in Table 1. On pages 7 and 8, various machine concepts are compared in tabular form. In chapter three, the paper is dedicated to the TRLs of current projects, the TRLs are focussed on the topic of superconductivity and the TRL levels are described and analysed in a very structured way. This results in a very valuable tool for designers of electrical machines with high power density demands. Tab. 4 summarises this procedure very well. In Tab. 5, projects on superconducting electrical machines are presented according to countries and technologies, so this table provides a very good overview. of the current state of knowledge and technology.The table is supplemented by a list of current patent specifications. The paper ends with a summary.In the summary, the very structured presentation is arranged once again.Overall, the paper provides a very clear, very structured overview of the subject area of TRL for superconducting electrical machines. In the last years several overview papers have been written on this topic. Nevertheless, the structured compilation here results in essential new elements and I highly recommend publishing the paper in its current form

Author Response

Thank you very much for your comments. If you have any more suggestions, let us know and we will gladly implement them in the text.

Reviewer 2 Report

This paper is well-written, comprehensive, and addresses a topic of growing interest. There are no significant issues in the paper, and it definitely warrants publication.

My only, (optional, leaving it to the authors' discretion) suggestion is related to the formatting of Table 4. As each TRL contains all the features of all lower levels, the use of the X symbols is somewhat redundant. Additionally, finding the corresponding TRL is somewhat difficult, as the X's are so tightly spaced.
The authors could consider e.g. a two-column format, where the left column lists the TRL, while the right one lists the features of the corresponding level, in a plus-all-of-the-above style.

Author Response

Thank you so much for your comments and for this suggestion. We have improved Table 4 to make it more readable.